Silicon steels containing selenium

ABSTRACT

DESCRIBED IS GRAIN ORIENTED SILICON STEEL HAVING A PREDOMINANTLY (110) (001) TEXTURE AND CRITICAL CARBON, MANGANESE AND SELENIUM QUANTITIES, I.E., 0.02% TO 0.07% CARBON, AT LEAST 0.045% MANGANESE 0.01% TO 0.1% SELENIUM AND NOT MORE THAN RESIDUAL SULFUR.

United States Patent 3,556,873 SILICON STEELS CONTAINING SELENIUM Frank A. Malagari, Jr., Freeport, Pa., assignor to Allegheny Ludlum Steel Corporation, Brackenridge, Pa., a corporation of Pennsylvania No Drawing. Filed Apr. 12, 1968, Ser. No. 721,099 Int. Cl. Htllf 1/16; C22c 39/46, 39/54 US. Cl. 148-3155 4 Claims ABSTRACT OF THE DISCLOSURE Described is grain oriented silicon steel having a predominantly 110) [001] texture and critical carbon, manganese and selenium quantities, i.e., 0.02% to 0.07% carbon, at least 0.045% manganese, 0.01% to 0.1% selenium and not more than residual sulfur.

properties of such steels.

In accordance with the invention, it has been discovered that selenium can be made to exercise a beneficial effect on the properties of silicon steel having not more than residual sulfur, if the carbon, manganese and selenium are critically controlled. -As is hereinafter described, manganese must be present in a carefully defined range for selenium to be beneficial for good texture development. While the phenomenon involved is not entirely 0.045% to 0.07% manganese, not more than residual sulfur, i.e., less than 0.008%, 0.01% to 0.1% selenium, preferably 0.02% to 0.08% selenium, and having a predominantly (110) [001] texture. Optimum properties of core loss and permeability are obtained by compositions having the nominal analysis 0.05% carbon, 0.06% manganese, 3.4% silicon, 0.04% selenium, 0.002% sulfur and 0.004% phosphorus, the balance essentially iron and other steel-making residuals. This composition has a 60 cycle core loss of 0.44 watt per pound at 15,000 gauss and a permeability at 10 oersteds of 1845.

The following examples will illustrate grain oriented silicon steels in accordance with the invention and the improved properties which they possess.

A series of samples of the compositions described in Table I were prepared by vacuum induction melting, hot rolled from ingot to band gauge, normalized, cold rolled to intermediate gauge, normalized and cold rolled to final gauge. After final cold rolling, the strip was given a decarburizing anneal.

TABLE I Master Group alloy C Mn P S Si So I RV-2184 030 060 004 003 3. 33 0. 14 RV-2185 053 060 004 002 3. 38 0. 13 III RV-2203 034 008 007 020 3. 0. 00 IV RV-2183 054 008 008 020 3. 33 0-. 096

TABLE II lerccii-h Percent Percent Percent WP]? 60- Group Heat Sc Mn S at 15 kb. my at 10 h.

Ill 2C1133 0 008 020 034 783 1565 2C1l34 01 008 020 034 681 1615 IV 2C1126 0 008 020 054 544 1729 201127 01 008 020 054 502 1677 *Data in parenthesis on a second series of samples of the same composition.

understood, it is believed to involve the formation of manganese selenide which is in turn responsible for the improved properties.

Grain oriented silicon steels within the purview of the invention are those containing 0.02% to 0.07% carbon, 2% to 4% silicon, at least 0.045% manganese, preferably It is evident from the data in Table II that low core loss with high permeability occurs in the 0.03% carbon series (Group I) at selenium contents of 0.06% and 0.08%. This group of samples also has a sulfur content in the residual range but the manganese content is 0.06%. Below or above this selenium range the core loss is higher with a corresponding decrease in permeability. However, if the carbon level is increased to 0.053%, as in the Group II higher silicon content detrimentally atlects the cold workability of the steel.

TABLE III Series N o. 1 Series No. 2 Sulfur Series 60- se0- Ann Sc, WPP at; y. at Aim Se, WPP at p. at Aim S, WPP at .1 at percent 15 kb. 11. percent kb. 10 h. percent 15 kb. 10 11 .551 1, 692 e as a a re 4 1, 6 a as 5 m samples, then the best core loss and permeability combination occurs at 0.02% and 0.04% selenium. Thus, it is possible to obtain excellent core loss at lower selenium levels if the carbon is increased to about the 0.05% level. Continued good core loss and permeability can be obtained with selenium contents of 0.08% and some deterioration in magnetic properties occurs at above about 0.1% selenium. It should be noted that the manganese content for the Group II samples was also about 0.06%.

The test results for the samples in Groups III and IV have higher sulfur, i.e., 0.2%, but very low manganese, i.e., 0.008%, together with selenium. The poor properties shown illustrate the importance of manganese control and that selenium is not beneficial in sulfur-containing steels. It has been determined that manganese levels below about 0.045% will not result in consistently satisfactory properties.

It has also been found that optimum properties in silicon steels in accordance with the invention are achieved at selenium levels of 0.02% to 0.08%. This is seen by the series of examples summarized in Table III which compares the electrical properties of selenium-containing steels with those of sulfur-containing steels. It is evident from the data in Table III that extremely low core losses can be obtained in selenium-bearing 3.25% silicon steels. It has also been determined by comparison with sulfurbearing steels that silicon would have to be increased to about 4% to achieve a comparable core loss level in sulfur-containing steels devoid of selenium. Of course,

The improved electrical properties in the silcon steel disclosed above and in the foregoing examples reflect the strong development of the (110) [001] texture. The development of this texture results in extremely low core loss with high permeability. Properties of the steels in accordance with the invention can be optimized by controlling the carbon content within the range of 0.03% to 0.053%.

It is apparent from the above that various changes and modifications may be made without departing from the invention. Accordingly, the scope of the invention should be limited only by the appended claims.

I claim:

1. Grain oriented silicon steel having a predominantly (110) [001] texture consisting essentially of 0.02% to 0.07% carbon, 2% to 4% silicon, at least 0.045% manganese, 0.01% to 0.1% selenium and less than about 0.008% sulphur.

2. Grain oriented silicon steel in accordance with claim 1 having 002% to 0.8% selenium.

3. Grain oriented silicon steel in accordance with claim 1 consisting essentially of 0.02% to 0.07% carbon, 2% to 4% silicon, 0.045% to 0.07% manganese, 0.02% to 0.08% selenium and not more than 0.008% sulphur.

4. Grain oriented silicon steel in accordance with claim 3 having, normally, 0.05% carbon, 0.06% manganese, 3.4% silicon and 0.04% selenium.

References Cited UNITED STATES PATENTS 2,867,557 1/1959 Crede et al 148111 3,151,005 9/1964 Alworth et al. 148-113 3,157,538 11/1964 Imal et al. 148110X L. DEWAYN-E RUTLEDGE, Primary Examiner G. K. WHITE, Assistant Examiner US. Cl. X.R. 

